Before going to the concept of Centrifugal Compressors, we need to have basic knowledge of fluid and mechanical principles governing the energy transfer used in centrifugal compressors. There exists vast number of machines which use air, steam and gas as working mediums.
The density of fluids gets changed with a change in temperature, as well as pressure. Pressure will be given the main role play in Centrifugal compressors. So the equations of energy transfer and the equations relating to Pressure, Temperature and Density must be considered. In general there are two types of compressors. We are now going to have a quick overview of Centrifugal Compressors.
A centrifugal compressor is invented during the times of Second World War. They are used in gas turbine units. It is usually a radial flow roto dynamic fluid machine which mostly works with air as a working fluid medium. It utilizes all the pressure imparted to the machine from outside to increase the internal energy of the fluid. But soon after the war, they realized axial compressors give appreciably high isentropic efficiency. Centrifugal compressors is the reborn interest in the Centrifugal stage.
A Centrifugal compressor primarily consists of
- Stationary casing
- Rotating Impeller
- Diffuser
Centrifugal compressor is also known as Radial Compressor. The gas enters the primary suction eye of this high speed rotary element known as impeller, which consists of radial vanes cast in it. As the impeller starts rotating, the blades on the impeller pushes the gas outwards from centre to open end of impeller. So a high pressure region is created which helps in the formation of compression. For perfect working of the compressor, it must be maintained in an oil seal environment.
Applications of Centrifugal Compressor
- Primarily used in Gas compressor components
- Gas path for Natural gas
- Off Shore platform applications
- Gas Re-injection via sub sea export pipeline
- Gas gathering
- Typical oil compression
- Gas shift system
- Hydraulic compressors for Industrial machines
Advantages Of Centrifugal Compressor
- Wide Operating ranges
- Very high reliability
- Low maintenance costs
- Low initial cost
- Medium Capacity storage
- High efficiency
Disadvantages Of Centrifugal Compressor
- Very unstable when the flow is reduced.
- Sensitive to changes in gas compositions
- Limited compression ratios
- Limited turn downs
- Periodic replacement is necessary for proper functioning
